Question

A boy is exerting a force of 70 N at a 50-degree angle on a lawn mower. He is accelerating at 1.8 m/s2. Round the answers to the nearest whole number.

What is the mass of the lawn mower?

⇒ 25 kg

What is the normal force exerted on the lawn mower?

⇒ 299 N

Answer 1

Explanation:

Given that,

Force, F = 70 N

Angle, $\theta=50^{\circ}$

Acceleration of the boy, a = 1.8 m/s²

(a) Net force is equal to the product of mass and acceleration. So,

$m=\dfrac{F}{a}\\\\m=\dfrac{70}{1.8}\\\\m=38.89\ kg$

(2) Normal force = upward force

So,

$F=mg\cos\theta\\\\F=38.89\times 9.81\times \cos(50)\\F=245.23\ N$

Hence, mass is 38.89 kg and the normal force is 245.23 N.